At College I had a locker. I can’t remember what brought it about but I decided that I should make it open via remote control. I designed the system but never managed to find all the parts I needed for free/ cheap enough.
I decided I wanted to use a solenoid to actuate the lock bolt and during my solenoid experiments I realised that if you time the current pulse correctly you can launch the armature a considerable distance. This got me thinking and in my subsequent research I discovered coil guns.
Soon after this I was given the opportunity for the College to provide all the necessary materials for me to make a physics project. I had struggled to get hold of some enamel coated wire for the remote locker project and thought this was the ideal opportunity to acquire some. I did some pezzy experiment into how the layers, length, thickness of wire, size of the core, voltage and current effected magnetic strength and received a reasonable mark for it.
I then recycled the wire from that project to build a 6mm coil gun.
An in depth explanation of how it works, what it does, and how to make one is available on instructables here: http://www.instructables.com/id/6mm-Coil-Gun/